Silicone polyethers are used in many applications, notably as surfactants and in the preparation of personal care products, polyurethanes and paint, ink and coating formulations. They may be produced by hydrosilation of a polyether initiated by an aliphatically unsaturated alcohol with a silicone having a SiH functionality. The polyether used may be produced from various initiators and epoxides under the influence of a variety of catalysts. Selection of the exact starting materials and routes utilized is important in determining the properties of the final polymer with even small changes producing very dramatic differences at times. The synthesis chosen for the polyether may be the most critical choice.
Bennett in U.S. Pat. Nos. 3,957,843 and 4,059,605 describes silicone based polyethers made using polyethers initiated by alkenyl alcohols. The polyethers were formed with a KOH catalyst. Japanese application, JP8-208426, appears to make a similar disclosure. Polymers such as these, especially those prepared from tertiary alcohols, are known to exhibit high polydispersity and at least those with polyethers based on ethylene oxide will tend to be waxes as opposed to liquids.
Alkynyl alcohol initiated polyethers are difficult if not impossible to make using a basic catalyst as there tends to be decomposition of the product, and there is also the issue of migration of the triple bond. Use of Lewis acids solves these problems to some extent, but results in formation of large amounts of difficult to remove byproducts and cyclization of the polyethers. An example in the art showing use of a Lewis acid catalyst in this context is U.S. Pat. No. 3,644,535 to Batty et al., while U.S. Pat. No. 5,066,756 to Raleigh et al. mentions use of acid and basic catalysts.
Use of metal cyanide type catalysts instead of conventional basic or Lewis acid catalysts may improve the situation. Use of cyanide and acid catalysts are described by Burkhart et al. in U.S. Pat. No. 5,391,679 for certain specific situations; the silicone was attached to the alcohol first to form the initiator. A similar initiator is described by Watabe et al. in EP 0485637 along with a metal cyanide catalyst, as well as fluorinated polyethers. Jorgenson et al. in U.S. Pat. Nos. 5,877,268 and 5,856,369 describe use of a metal cyanide catalyst focusing mostly on allyl and methallyl alcohol initiated polyethers; use of metal cyanide catalyst is criticized in some cases there, however.
Harper et al. in U.S. Pat. No. 4,877,906 describes a method of removing metal cyanide catalysts from polyethers after their formation.
There is a need for new silicone based polyethers, perhaps especially those with multi-functionality and/or low polydispersity. This invention is directed to this need among others.